Diesel engines provide lower emissions and increased fuel economy compared to gasoline engines; however, untreated diesel exhaust emissions are generally undesirable. Diesel particulate filters have been employed to control/treat particulate emissions from diesel-powered equipment such as trucks, buses, diesel powered ships, diesel electric locomotives and generators. Diesel particulate filters control diesel particulate emissions by physically trapping soot particles in their structures.
A typical diesel particulate filter body may be, for example, a honeycomb structure having a matrix of intersecting thin, porous walls that extend across and between its two opposing open end faces and form a large number of adjoining hollow passages, or cells, which also extend between and are open at the end faces. To form a filter, a first subset of cells is closed at one end face, and the remaining cells are closed at the other end face. A contaminated gas is brought under pressure to one face (the “inlet face”) and enters the filter body via the cells that are open at the inlet face (the “inlet cells”). Because the inlet cells are sealed at the remaining end face (the “outlet face”) of the body, the contaminated gas is forced through the thin, porous walls into adjoining cells that are sealed at the inlet face and open at the opposing outlet face of the filter body (the “outlet cells”). The solid particulate contaminants in the exhaust gas (such as soot), which are too large to pass through the porous openings in the walls, are left behind, and cleaned exhaust gas exits the outlet face of the filter body through the outlet cells.
Such diesel filters are typically formed by an extrusion process where a ceramic material is extruded into a green form before the green form is fired to form the final ceramic material of the filter. These extruded green forms can be any size or shape.
Green, unfired ceramic forms, as well as fired ceramic forms are readily damaged in the course of handling these objects during and after manufacture. Damage often occurs on the edges of these forms due to the mechanical stresses of contacting the forms with surfaces. Chipped and damaged forms are a significant source of handing losses in manufacturing plants and in the supply chain.
Accordingly, providing ceramic honeycomb structures which are less susceptible to mechanical damage is desired. Likewise, methods of manufacturing ceramic honeycomb structures which are less susceptible to mechanical damage are also desired.